GB829559A - Preparation of high molecular weight materials - Google Patents

Abstract

Relates to the preparation of materials of high molecular weight from an aqueous mixture of metal compounds or silica particles having dimensions in the range of 4-120 microns, a smaller amount of colloidal silica and a still smaller amount of dissolved silica. The materials thus prepared may be used in drawing glass-like fibres, in making flexible films or weatherproofing layers, in bonding glass-fibre batts, and in making proteins. The mixture is preferably stabilized by a minor amount of an organosiliconate (monomeric silanolate), an organic hydrophilic material having a molecular weight of at least 10,000 and an organic hydrophobic material having a molecular weight of at least 5000. For the preparation of glass fibres 18 parts each of monomeric ethyl methacrylate and monomeric vinyl acetate are polymerized, copolymerized, reacted and digested in 70 parts of an aqueous solution of 35% acetic acid at 180 DEG F. The reaction products (A) form the hydrophilic material. A mixture is made containing 85% A, 1 1/3 % sodium methyl siliconate solution and 12% of a partially converted polydimethylsiloxane. This mixture (B) is diluted with 25 vols. of water and sufficient conc. NH4OH is added rapidly and agitated to obtain a pH of 9.5. This is called C. An alkaline dispersion (D) of natural rubber latex to correspond, on a solids content basis, to 5 parts of solids is added to such quantity of C as corresponds to 3 parts solids to form 8 parts of a solution (E), the pH being kept constant at 9.5 by addition of NH4OH and agitation. This mixture E is the stabilizing agent, the dispersion D being the hydrophobic material. Instead of natural rubber being used for dispersion D, synthetic rubber, starch ethers, starch esters, butyl acrylate and related materials may be used. A slurry (F) is formed from ground inorganic materials and water; the ground materials may be an opacifying enamel frit comprising ZrO2 45%, ZnO 22, B2O3 14, SiO2 10, TiO2 1.0, CaF2 3.3, Al2O3+MgO 0.7 and Na2O 4.0. A colloidal solution (G) of SiO2 containing dissolved silica is made, the colloidal SiO2 comprising about 9% of the solution. A mixture (H) of one volume of F, two volumes of G and less than 2% (by weight of metal oxides) of E is then made. H is now de-aerated by bubbling gaseous NH4OH through the mixture, and this then forms the glass-fibre spinning syrup I. In the preparation of the hydrophilic mixture B, instead of the sodium methyl siliconate the potassium salt may be used; also salts of ethyl, isopropyl or phenyl siliconate acids may be used, and instead of the polydimethylsiloxane the copolymer formed by subjecting equal parts of hexamethyltrisiloxane, terephthalic acid, and sorbitol to high temperature acidic polymerization conditions may be used, or other copolymers of alkyds, phenolic resins and silicones are suitable. The glass fibres may be drawn from solution I by introducing the point of a wood sliver therein and slowly withdrawing it; it is stated that the fibre thus formed is simultaneously dehydrated and the theory of proton transfer is discussed. Alternatively, the solution may be extruded through a metallic orifice into an electrostatic field. For weatherproofing (e.g. gypsum or concrete building blocks) a coating of solution H of about 300 microns thickness is applied. After the volatile components have evaporated further layers of solution H are applied. Batts of glass fibres may be sprayed with a solution of solution I in five parts of water and the water evaporated to bind the fibres at some of their points of contact.ALSO:Relates to the preparation of proteins using materials of high molecular weight prepared from an aqueous mixture of metal compounds or silica particles having dimensions in the range of 4-120 microns, a smaller amount of colloidal silica and a still smaller amount of dissolved silica. The mixture is preferably stabilized by a minor amount of an organosiliconate (monomeric silanolate), an organic hydrophilic material having a molecular weight of at least 10,000 and an organic hydrophobic material having a molecular weight of an least 5000. Reaction products (A) formed by digesting a vinyl acetate-ethyl methacrylate copolymer in acetic acid, form the hydrophilic material. A mixture is made containing 85% (A), 1 1 3 % sodium methyl siliconate solution, and 12% of a partially converted polydimethylsiloxane. This mixture (B) is diluted with 25 vols. of water and sufficient conc. NH4OH is added rapidly and agitated to obtain a pH of 9.5. This is called C. An alkaline dispersion (D) of natural rubber latex to correspond, on a solids content basis, to 5 parts of solids is added to such quantity of C as corresponds to 3 parts solids to form 8 parts of a solution (E), the pH being kept constant at 9.5 by addition of NH4OH and agitation. This mixture E is the stabilizing agent, the dispersion D being the hydrophobic material. Instead of natural rubber being used for dispersion D, synthetic rubber, starch ethers, starch esters, butyl acrylate and related materials may be used. In the preparation of the hydrophilic mixture B, instead of the sodium methyl siliconate the potassium salt may be used; also salts of ethyl, isopropyl or phenyl siliconate acids may be used, and instead of the polydimethylsiloxane the copolymer formed by subjecting equal parts of hexamethyltrisiloxane, terephthalic acid, and sorbitol to high temperature acidic polymerization conditions may be used, or other copolymers of alkyds, phenolic resins and silicones are suitable. Proteins may be formed by adding a dispersion of amino acids in water containing less than 5% ammonium acetate to a colloidal silica suspension containing dissolved silica to which small quantities of metal hydroxides have been added. Up to 2%, by weight of the silica, of solution E is added and after the silica has been removed the residue is found to contain a mixture of polyamino/acids containing peptide linkage.